Jet.com offers the Microsoft Surface Bluetooth Wireless Keyboard for $67.69 with free shipping. (Amazon charges pennies less the same.) That's the lowest price we could find by $31. It features Bluetooth 4.0 and is compatible Windows, Mac OS, and Android.

Note: You can also receive additional discounts during checkout by waiving free returns or by choosing select payment options.

Update: Amazon now offers it for $64.01 with free shipping.